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  #1  
Old 12-03-2018, 05:37 PM
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Dark tube.

I dont know if this works but the idea is to eliminate stray light from getting down to the lens.

Think of it as a dew tube with baffles I was concerned about stray light and this was what I came up with.

After I built my first one I noticed that the Hubble Space telescope employs a similar idea... but I think if nothing else it helps cut out light from the street light opposite my spot in Sydney.

I used cardboard and paper towels for the build and some glue was just flour salt and water but when dry I painted that with resin which turns the paper towel into a very strong medium.
Alex
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  #2  
Old 12-03-2018, 05:46 PM
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The last shot is to show how intrusive the light across the road.
Alex
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  #3  
Old 12-03-2018, 05:48 PM
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I took these photos with a flash , some of them, whilst imaging and the flash I think was nutralised by the tube on review of the images.
Alex
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  #4  
Old 12-03-2018, 05:51 PM
JA
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Quote:
Originally Posted by xelasnave View Post
I dont know if this works but the idea is to eliminate stray light from getting down to the lens.
Absolutely will work Alex, just like a big lens hood and it will increase contrast (compared with an unprotected lens) by removing that stray light glancing in to the optics near the edge of the frame.

Good result.

Best
JA
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  #5  
Old 12-03-2018, 07:49 PM
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Quote:
Originally Posted by JA View Post
Absolutely will work Alex, just like a big lens hood and it will increase contrast (compared with an unprotected lens) by removing that stray light glancing in to the optics near the edge of the frame.

Good result.

Best
JA
Well if nothing else it has me not focused on the street light as mentally I have eliminated it..it is a piece of mind thing.

And its funny given where I come from the best dark site ever...but I built it to manage the star light getting down the tube...

I look at it this way ..when you see that the canon lens used in the dragon fly array is wonderful because it has less internal reflection than anything else ..well stray light must be important....But I need to do a test...

Persoanlly even without the test I would say to anyone to build and fit one I just think it is that much better.

alex
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  #6  
Old 14-03-2018, 05:02 PM
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My Astro binocs have got light baffle tubes on the front, about 50mm long. Makes a big difference with sidelight intrusion and reflections. Just used a couple of plastic cutoffs from some toner bottles I had lying around.
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  #7  
Old 14-03-2018, 10:01 PM
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Made one for the camera 70 /300 mm lens and added a little foam and this baby one fits the finder guider...matching set.
I think it could help with a camera lens ..will see soon.
alex
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  #8  
Old 15-03-2018, 06:26 AM
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Yep it works, its why i always use the lens hoods that came with my lenses, its to keep that stray light from touching the front glass.
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  #9  
Old 15-03-2018, 08:23 AM
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Thanks Sil for your observation.

Some photos.

Alex
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  #10  
Old 25-03-2018, 05:22 PM
N5SE (Sal)
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clever
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